We know, that the <span>area of the surface generated by revolving the curve y about the x-axis is given by:
In this case a = 0, b = 15,
and:
So there will be:
![\left(\star\right)=\dfrac{2\pi}{15}\cdot\int\limits_0^{15}x^3\cdot\sqrt{1+\dfrac{x^4}{25}}\,\, dx=\dfrac{2\pi}{15}\cdot\dfrac{25}{6}\cdot\left[\left(1+\dfrac{x^4}{25}\right)^\frac{3}{2}\right]_0^{15}=\\\\\\= \dfrac{5\pi}{9}\left[\left(1+\dfrac{15^4}{25}\right)^\frac{3}{2}-\left(1+\dfrac{0^4}{25}\right)^\frac{3}{2}\right]=\dfrac{5\pi}{9}\left[2026^\frac{3}{2}-1^\frac{3}{2}\right]=\\\\\\= \boxed{\dfrac{5\Big(2026^\frac{3}{2}-1\Big)}{9}\pi}](https://tex.z-dn.net/?f=%5Cleft%28%5Cstar%5Cright%29%3D%5Cdfrac%7B2%5Cpi%7D%7B15%7D%5Ccdot%5Cint%5Climits_0%5E%7B15%7Dx%5E3%5Ccdot%5Csqrt%7B1%2B%5Cdfrac%7Bx%5E4%7D%7B25%7D%7D%5C%2C%5C%2C%20dx%3D%5Cdfrac%7B2%5Cpi%7D%7B15%7D%5Ccdot%5Cdfrac%7B25%7D%7B6%7D%5Ccdot%5Cleft%5B%5Cleft%281%2B%5Cdfrac%7Bx%5E4%7D%7B25%7D%5Cright%29%5E%5Cfrac%7B3%7D%7B2%7D%5Cright%5D_0%5E%7B15%7D%3D%5C%5C%5C%5C%5C%5C%3D%0A%5Cdfrac%7B5%5Cpi%7D%7B9%7D%5Cleft%5B%5Cleft%281%2B%5Cdfrac%7B15%5E4%7D%7B25%7D%5Cright%29%5E%5Cfrac%7B3%7D%7B2%7D-%5Cleft%281%2B%5Cdfrac%7B0%5E4%7D%7B25%7D%5Cright%29%5E%5Cfrac%7B3%7D%7B2%7D%5Cright%5D%3D%5Cdfrac%7B5%5Cpi%7D%7B9%7D%5Cleft%5B2026%5E%5Cfrac%7B3%7D%7B2%7D-1%5E%5Cfrac%7B3%7D%7B2%7D%5Cright%5D%3D%5C%5C%5C%5C%5C%5C%3D%0A%5Cboxed%7B%5Cdfrac%7B5%5CBig%282026%5E%5Cfrac%7B3%7D%7B2%7D-1%5CBig%29%7D%7B9%7D%5Cpi%7D)
Answer C.
</span>
Answer:
B). 3 1/2(-2) = -7
Step-by-step explanation:
Let's evaluate the expression so as to be able to get the right estimate.
3 4/7 (-2 1/12)
=3 4/7 (-25/12)
= 25/7 * -25/12
= 25/7 * -25/12
= -625/84
= -7 37/84
Approximately it's equal to ,-7
ANSWER:
x = 10 / 3
y = 0
STEP-BY-STEP EXPLANATION:
We will be using simultaneous equations to solve this problem. Let's first establish the two equations which we will be using.
Equation No. 1 -
- 6x - 14y = - 20
Equation No. 2 -
- 3x - 7y = - 10
First, we will make ( x ) the subject in the first equation and simplify accordingly.
Equation No. 1 -
- 6x - 14y = - 20
- 6x = - 20 + 14y
x = ( - 20 + 14y ) / - 6
x = ( - 10 + 7y ) / - 3
From this, we will make ( y ) the subject in the second equation and substitute the value of ( x ) from the first equation into the second equation to solve for ( y ) accordingly.
Equation No. 2 -
- 3x - 7y = - 10
- 7y = - 10 + 3x
- 7y = - 10 + 3 [ ( - 10 + 7y ) / - 3 ]
- 7y = - 10 + [ ( - 30 + 21y ) / - 3 ]
- 7y = - 10 + ( 10 - 7y )
- 7y = - 7y
- 7y + 7y = 0
0y = 0
y = 0
Using this, we will substitute the value of ( y ) from the second equation into the first equation to solve for ( x ) accordingly.
x = ( - 10 + 7y ) / - 3
x = [ - 10 + 7 ( 0 ) ] / - 3
x = [ - 10 + 0 ] / - 3
x = - 10 / - 3
x = 10 / 3
